Articulation state detection mechanisms

ABSTRACT

A surgical shaft assembly includes a proximal shaft portion, a distal shaft portion, and a control circuit. The proximal shaft portion includes a first sensor generating a first signal and a second sensor generating a second signal. The distal shaft portion includes a clutch assembly rotatable with the distal shaft portion about a longitudinal axis and relative to the proximal shaft portion. The clutch assembly is further rotatable relative to the distal shaft portion to transition the shaft assembly between two articulation states. The rotation of clutch assembly with the distal shaft portion changes the first signal, and the rotation of the clutch assembly relative to the distal shaft portion changes the second signal. The control circuit is configured to detect a change in the second signal occurring without a corresponding change in the first signal. The detected change indicates a transition between the two articulation states.

TECHNICAL FIELD

The present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue.

BACKGROUND

In a motorized surgical stapling and cutting instrument it may be useful to measure the position and velocity of a cutting member in an initial predetermined time or displacement to control speed. Measurement of position or velocity over an initial predetermined time or displacement may be useful to evaluate tissue thickness and to adjust the speed of the remaining stroke based on this comparison against a threshold.

While several devices have been made and used, it is believed that no one prior to the inventors has made or used the device described in the appended claims.

SUMMARY

A shaft assembly is usable with a surgical instrument. The shaft assembly defines a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly includes a proximal shaft portion including a first sensor and a second sensor. The shaft assembly also includes a distal shaft portion rotatable about the longitudinal axis and relative to the proximal shaft portion. The distal shaft portion includes housing, a first magnet rotatable with the housing, a clutch assembly rotatable relative to the housing to transition the shaft assembly between an articulation engaged state and an articulation disengaged state, and a second magnet rotatable with the clutch assembly. The shaft assembly further includes a control circuit configured to detect a transition from the articulation engaged state to the articulation disengaged state based on output signals from the first sensor and the second sensor.

A shaft assembly is usable with a surgical instrument. The shaft assembly defines a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly includes a proximal shaft portion including a first sensor and a second sensor. The shaft assembly also includes a distal shaft portion rotatable about the longitudinal axis and relative to the proximal shaft portion. The distal shaft portion includes a housing, a first magnet rotatable with the housing, a clutch assembly rotatable relative to the housing to transition the shaft assembly between an articulation engaged state and an articulation disengaged state, and a second magnet rotatable with the clutch assembly. The shaft assembly further includes a control circuit configured to detect a transition from the articulation engaged state to the articulation disengaged state based on relative rotational positions of the distal shaft portion of the shaft assembly and the clutch assembly.

A shaft assembly is usable with a surgical instrument. The shaft assembly defines a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly includes a proximal shaft portion including a first sensor configured to generate a first output signal and a second sensor configured to generate a second output signal. The shaft assembly also includes a distal shaft portion. The distal shaft portion includes a clutch assembly rotatable with the distal shaft portion about the longitudinal axis and relative to the proximal shaft portion. The clutch assembly is further rotatable relative to the distal shaft portion to transition the shaft assembly between an articulation engaged state and an articulation disengaged state. The rotation of clutch assembly with the distal shaft portion changes the first output signal. The rotation of the clutch assembly relative to the distal shaft portion changes the second output signal. The shaft assembly also includes a control circuit in electrical communication with the first sensor and the second sensor, wherein the control circuit is configured to detect a change in the second output signal occurring without a corresponding change in the first output signal, and wherein the detected change indicates a transition between the articulation engaged state and the articulation disengaged state.

FIGURES

The novel features of the various aspects described herein are set forth with particularity in the appended claims. The various aspects, however, both as to organization and methods of operation may be better understood by reference to the following description, taken in conjunction with the accompanying drawings as follows:

FIG. 1 is a perspective view of a surgical instrument that has a shaft assembly and an end effector in accordance with one or more aspects of the present disclosure.

FIG. 2 is an exploded assembly view of a portion of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 3 is an exploded view of an end effector of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 4 is perspective view of an RF cartridge and an elongate channel adapted for use with the RF cartridge according to one aspect of the present disclosure.

FIG. 5 is an exploded assembly view of portions of the interchangeable shaft assembly of the surgical instrument of FIG. 1 according to one aspect of this disclosure.

FIG. 6 is another exploded assembly view of portions of the interchangeable shaft assembly of FIG. 1 according to one aspect of this disclosure.

FIG. 7 is a cross-sectional view of a portion of the interchangeable shaft assembly of FIG. 1 according to one aspect of this disclosure.

FIG. 8 is a perspective view of a portion of the shaft assembly of FIG. 1 with the switch drum omitted for clarity.

FIG. 9 is another perspective view of the portion of the interchangeable shaft assembly of FIG. 1 with the switch drum mounted thereon.

FIG. 10 is a partial perspective view of a shaft assembly according to one aspect of this disclosure.

FIG. 11 is a table indicating the movement or lack thereof of several components of the shaft assembly of FIG. 10 during user-controlled shaft rotation and during a change in an articulation engagement state of the shaft assembly of FIG. 10.

FIGS. 12-14 are partial perspective views of the shaft assembly of FIG. 10 showing an engaged articulation engagement state (FIG. 12), an intermediate articulation engagement state (FIG. 13), and a disengaged articulation engagement state (FIG. 14).

FIGS. 15-17 are partial cross sectional view of the shaft assembly of FIG. 10 showing an engaged articulation engagement state (FIG. 15), an intermediate articulation engagement state (FIG. 16), and a disengaged articulation engagement state (FIG. 17).

FIG. 18 is a partial exploded view of a shaft assembly according to one aspect of this disclosure.

FIG. 19 is a partial cross-sectional view of the shaft assembly of FIG. 18.

FIG. 20 illustrates relative rotational positions of two permanent magnets of the shaft assembly of FIG. 18 in an articulation engaged state.

FIG. 21 illustrates relative rotational positions of two permanent magnets of the shaft assembly of FIG. 18 in an articulation disengaged state.

FIG. 22 is a circuit diagram illustrating a control circuit for use with the shaft assembly of FIG. 18 according to one aspect of this disclosure.

FIG. 23 is a partial perspective view of a shaft assembly according to one aspect of this disclosure.

FIG. 24 is another partial perspective view of the shaft assembly of FIG. 23.

FIG. 25 is a circuit diagram illustrating a control circuit for use with the shaft assembly of FIG. 23 according to one aspect of this disclosure.

DESCRIPTION

Applicant of the present application owns the following U.S. Patent Applications that were filed on even date herewith and which are each herein incorporated by reference in their respective entireties:

U.S. patent application Ser. No. ______, entitled SURGICAL SHAFT ASSEMBLIES WITH INCREASED CONTACT PRESSURE; Attorney Docket No. END8177USNP/170050;

U.S. patent application Ser. No. ______, entitled SURGICAL SHAFT ASSEMBLIES WITH SLIP RING ASSEMBLIES FORMING CAPACITIVE CHANNELS; Attorney Docket No. END8178USNP/170051;

U.S. patent application Ser. No. ______, entitled METHOD OF COATING SLIP RINGS; Attorney Docket No. END8179USNP/170052M;

U.S. patent application Ser. No. ______, entitled SURGICAL SHAFT ASSEMBLIES WITH WATERTIGHT HOUSINGS; Attorney Docket No. END8180USNP/170053; and

U.S. patent application Ser. No. ______, entitled SURGICAL SHAFT ASSEMBLIES WITH FLEXIBLE INTERFACES; Attorney Docket No. END8223USNP/170126.

Certain aspects are shown and described to provide an understanding of the structure, function, manufacture, and use of the disclosed devices and methods. Features shown or described in one example may be combined with features of other examples and modifications and variations are within the scope of this disclosure.

The terms “proximal” and “distal” are relative to a clinician manipulating the handle of the surgical instrument where “proximal” refers to the portion closer to the clinician and “distal” refers to the portion located further from the clinician. For expediency, spatial terms “vertical,” “horizontal,” “up,” and “down” used with respect to the drawings are not intended to be limiting and/or absolute, because surgical instruments can used in many orientations and positions.

The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a surgical system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more elements possesses those one or more elements, but is not limited to possessing only those one or more elements. Likewise, an element of a system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features.

Example devices and methods are provided for performing laparoscopic and minimally invasive surgical procedures. Such devices and methods, however, can be used in other surgical procedures and applications including open surgical procedures, for example. The surgical instruments can be inserted into a through a natural orifice or through an incision or puncture hole formed in tissue. The working portions or end effector portions of the instruments can be inserted directly into the body or through an access device that has a working channel through which the end effector and elongated shaft of the surgical instrument can be advanced.

FIGS. 1-9 depict a motor-driven surgical instrument 10 for cutting and fastening that may or may not be reused. In the illustrated examples, the surgical instrument 10 includes a housing 12 that comprises a handle assembly 14 that is configured to be grasped, manipulated, and actuated by the clinician. The housing 12 is configured for operable attachment to an interchangeable shaft assembly 200 that has an end effector 300 operably coupled thereto that is configured to perform one or more surgical tasks or procedures. In accordance with the present disclosure, various forms of interchangeable shaft assemblies may be effectively employed in connection with robotically controlled surgical systems. The term “housing” may encompass a housing or similar portion of a robotic system that houses or otherwise operably supports at least one drive system configured to generate and apply at least one control motion that could be used to actuate interchangeable shaft assemblies. The term “frame” may refer to a portion of a handheld surgical instrument. The term “frame” also may represent a portion of a robotically controlled surgical instrument and/or a portion of the robotic system that may be used to operably control a surgical instrument. Interchangeable shaft assemblies may be employed with various robotic systems, instruments, components, and methods disclosed in U.S. Pat. No. 9,072,535, entitled SURGICAL STAPLING INSTRUMENTS WITH ROTATABLE STAPLE DEPLOYMENT ARRANGEMENTS, which is herein incorporated by reference in its entirety.

FIG. 1 is a perspective view of a surgical instrument 10 that has an interchangeable shaft assembly 200 operably coupled thereto according to one aspect of this disclosure. The housing 12 includes an end effector 300 that comprises a surgical cutting and fastening device configured to operably support a surgical staple cartridge 304 therein. The housing 12 may be configured for use in connection with interchangeable shaft assemblies that include end effectors that are adapted to support different sizes and types of staple cartridges, have different shaft lengths, sizes, and types. The housing 12 may be employed with a variety of interchangeable shaft assemblies, including assemblies configured to apply other motions and forms of energy such as, radio frequency (RF) energy, ultrasonic energy, and/or motion to end effector arrangements adapted for use in connection with various surgical applications and procedures. The end effectors, shaft assemblies, handles, surgical instruments, and/or surgical instrument systems can utilize any suitable fastener, or fasteners, to fasten tissue. For instance, a fastener cartridge comprising a plurality of fasteners removably stored therein can be removably inserted into and/or attached to the end effector of a shaft assembly.

The handle assembly 14 may comprise a pair of interconnectable handle housing segments 16, 18 interconnected by screws, snap features, adhesive, etc. The handle housing segments 16, 18 cooperate to form a pistol grip portion 19 that can be gripped and manipulated by the clinician. The handle assembly 14 operably supports a plurality of drive systems configured to generate and apply control motions to corresponding portions of the interchangeable shaft assembly that is operably attached thereto.

FIG. 2 is an exploded assembly view of a portion of the surgical instrument 10 of FIG. 1 according to one aspect of this disclosure. The handle assembly 14 may include a frame 20 that operably supports a plurality of drive systems. The frame 20 can operably support a “first” or closure drive system 30, which can apply closing and opening motions to the interchangeable shaft assembly 200. The closure drive system 30 may include an actuator such as a closure trigger 32 pivotally supported by the frame 20. The closure trigger 32 is pivotally coupled to the handle assembly 14 by a pivot pin 33 to enable the closure trigger 32 to be manipulated by a clinician. When the clinician grips the pistol grip portion 19 of the handle assembly 14, the closure trigger 32 can pivot from a starting or “unactuated” position to an “actuated” position and more particularly to a fully compressed or fully actuated position.

The handle assembly 14 and the frame 20 may operably support a firing drive system 80 configured to apply firing motions to corresponding portions of the interchangeable shaft assembly attached thereto. The firing drive system 80 may employ an electric motor 82 located in the pistol grip portion 19 of the handle assembly 14. The electric motor 82 may be a DC brushed motor having a maximum rotational speed of approximately 25,000 RPM, for example. In other arrangements, the motor may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The electric motor 82 may be powered by a power source 90 that may comprise a removable power pack 92. The removable power pack 92 may comprise a proximal housing portion 94 configured to attach to a distal housing portion 96. The proximal housing portion 94 and the distal housing portion 96 are configured to operably support a plurality of batteries 98 therein. Batteries 98 may each comprise, for example, a Lithium Ion (LI) or other suitable battery. The distal housing portion 96 is configured for removable operable attachment to a control circuit board 100, which is operably coupled to the electric motor 82. Several batteries 98 connected in series may power the surgical instrument 10. The power source 90 may be replaceable and/or rechargeable.

The electric motor 82 can include a rotatable shaft (not shown) that operably interfaces with a gear reducer assembly 84 mounted in meshing engagement with a with a set, or rack, of drive teeth 122 on a longitudinally movable drive member 120. The longitudinally movable drive member 120 has a rack of drive teeth 122 formed thereon for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84.

In use, a voltage polarity provided by the power source 90 can operate the electric motor 82 in a clockwise direction wherein the voltage polarity applied to the electric motor by the battery can be reversed in order to operate the electric motor 82 in a counter-clockwise direction. When the electric motor 82 is rotated in one direction, the longitudinally movable drive member 120 will be axially driven in the distal direction “DD.” When the electric motor 82 is driven in the opposite rotary direction, the longitudinally movable drive member 120 will be axially driven in a proximal direction “PD.” The handle assembly 14 can include a switch that can be configured to reverse the polarity applied to the electric motor 82 by the power source 90. The handle assembly 14 may include a sensor configured to detect the position of the longitudinally movable drive member 120 and/or the direction in which the longitudinally movable drive member 120 is being moved.

Actuation of the electric motor 82 can be controlled by a firing trigger 130 that is pivotally supported on the handle assembly 14. The firing trigger 130 may be pivoted between an unactuated position and an actuated position.

Turning back to FIG. 1, the interchangeable shaft assembly 200 includes an end effector 300 comprising an elongated channel 302 configured to operably support a surgical staple cartridge 304 therein. The end effector 300 may include an anvil 306 that is pivotally supported relative to the elongated channel 302. The interchangeable shaft assembly 200 may include an articulation joint 270. Construction and operation of the end effector 300 and the articulation joint 270 are set forth in U.S. Patent Application Publication No. 2014/0263541, entitled ARTICULATABLE SURGICAL INSTRUMENT COMPRISING AN ARTICULATION LOCK, which is herein incorporated by reference in its entirety. The interchangeable shaft assembly 200 may include a proximal housing or nozzle 201 comprised of nozzle portions 202, 203. The interchangeable shaft assembly 200 may include a closure tube 260 extending along a shaft axis SA that can be utilized to close and/or open the anvil 306 of the end effector 300.

Turning back to FIG. 1, the closure tube 260 is translated distally (direction “DD”) to close the anvil 306, for example, in response to the actuation of the closure trigger 32 in the manner described in the aforementioned reference U.S. Patent Application Publication No. 2014/0263541. The anvil 306 is opened by proximally translating the closure tube 260. In the anvil-open position, the closure tube 260 is moved to its proximal position.

FIG. 3 is an exploded view of one aspect of an end effector 300 of the surgical instrument 10 of FIG. 1 in accordance with one or more aspects of the present disclosure. The end effector 300 may include the anvil 306 and the surgical staple cartridge 304. In this non-limiting example, the anvil 306 is coupled to an elongated channel 302. For example, apertures 199 can be defined in the elongated channel 302 which can receive pins 152 extending from the anvil 306 and allow the anvil 306 to pivot from an open position to a closed position relative to the elongated channel 302 and surgical staple cartridge 304. A firing bar 172 is configured to longitudinally translate into the end effector 300. The firing bar 172 may be constructed from one solid section, or in various examples, may include a laminate material comprising, for example, a stack of steel plates. The firing bar 172 comprises an E-beam 178 and a cutting edge 182 at a distal end thereof. In various aspects, the E-beam may be referred to as an I-beam. A distally projecting end of the firing bar 172 can be attached to the E-beam 178 element in any suitable manner and can, among other things, assist in spacing the anvil 306 from a surgical staple cartridge 304 positioned in the elongated channel 302 when the anvil 306 is in a closed position. The E-beam 178 also can include a sharpened cutting edge 182 that can be used to sever tissue as the E-beam 178 is advanced distally by the firing bar 172. In operation, the E-beam 178 also can actuate, or fire, the surgical staple cartridge 304. The surgical staple cartridge 304 can include a molded cartridge body 194 that holds a plurality of staples 191 resting upon staple drivers 192 within respective upwardly open staple cavities 195. A wedge sled 190 is driven distally by the E-beam 178, sliding upon a cartridge tray 196 that holds together the various components of the surgical staple cartridge 304. The wedge sled 190 upwardly cams the staple drivers 192 to force out the staples 191 into deforming contact with the anvil 306 while the cutting edge 182 of the E-beam 178 severs clamped tissue.

The E-beam 178 can include upper pins 180 that engage the anvil 306 during firing. The E-beam 178 can further include middle pins 184 and a bottom foot 186 that can engage various portions of the cartridge body 194, cartridge tray 196, and elongated channel 302. When a surgical staple cartridge 304 is positioned within the elongated channel 302, a slot 193 defined in the cartridge body 194 can be aligned with a longitudinal slot 197 defined in the cartridge tray 196 and a slot 189 defined in the elongated channel 302. In use, the E-beam 178 can slide through the aligned longitudinal slots 193, 197, and 189 wherein, as indicated in FIG. 3, the bottom foot 186 of the E-beam 178 can engage a groove running along the bottom surface of elongated channel 302 along the length of slot 189, the middle pins 184 can engage the top surfaces of cartridge tray 196 along the length of longitudinal slot 197, and the upper pins 180 can engage the anvil 306. In such circumstances, the E-beam 178 can space, or limit the relative movement between, the anvil 306 and the surgical staple cartridge 304 as the firing bar 172 is moved distally to fire the staples from the surgical staple cartridge 304 and/or incise the tissue captured between the anvil 306 and the surgical staple cartridge 304. Thereafter, the firing bar 172 and the E-beam 178 can be retracted proximally allowing the anvil 306 to be opened to release the two stapled and severed tissue portions.

Referring to FIG. 4, in at least one arrangement, an interchangeable shaft assembly can be used in connection with an RF cartridge 1700 as well as a surgical staple/fastener cartridge.

The RF surgical cartridge 1700 includes a cartridge body 1710 that is sized and shaped to be removably received and supported in the elongate channel 1602. For example, the cartridge body 1710 may be configured to be removable retained in snap engagement with the elongate channel 1602. In at least one aspect, the cartridge body 1710 includes a centrally disposed elongate slot 1712 that extends longitudinally through the cartridge body to accommodate longitudinal travel of a knife therethrough.

The cartridge body 1710 is formed with a centrally disposed raised electrode pad 1720. The elongate slot 1712 extends through the center of the electrode pad 1720 and serves to divide the pad 1720 into a left pad segment 1720L and a right pad segment 1720R. A right flexible circuit assembly 1730R is attached to the right pad segment 1720R and a left flexible circuit assembly 1730L is attached to the left pad segment 1720L. In at least one arrangement for example, the right flexible circuit 1730R comprises a plurality of wires 1732R that may include, for example, wider wires/conductors for RF purposes and thinner wires for conventional stapling purposes that are supported or attached or embedded into a right insulator sheath/member 1734R that is attached to the right pad 1720R. In addition, the right flexible circuit assembly 1730R includes a “phase one”, proximal right electrode 1736R and a “phase two” distal right electrode 1738R. Likewise, the left flexible circuit assembly 1730L comprises a plurality of wires 1732L that may include, for example, wider wires/conductors for RF purposes and thinner wires for conventional stapling purposes that are supported or attached or embedded into a left insulator sheath/member 1734L that is attached to the left pad 1720L. In addition, the left flexible circuit assembly 1730L includes a “phase one”, proximal left electrode 1736L and a “phase two” distal left electrode 1738L. The left and right wires 1732L, 1732R are attached to a distal micro-chip 1740 mounted to the distal end portion of the cartridge body 1710.

The elongate channel 1602 includes a channel circuit 1670 that is supported in a recess 1621 that extends from the proximal end of the elongate channel 1602 to a distal location 1623 in the elongate channel bottom portion 1620. The channel circuit 1670 includes a proximal contact portion 1672 that contacts a distal contact portion 1169 of a flexible shaft circuit strip for electrical contact therewith. A distal end 1674 of the channel circuit 1670 is received within a corresponding wall recess 1625 formed in one of the channel walls 1622 and is folded over and attached to an upper edge 1627 of the channel wall 1622. A serial of corresponding exposed contacts 1676 are provided in the distal end 1674 of the channel circuit 1670. An end of a flexible cartridge circuit 1750 is attached to the distal micro-chip 1740 and is affixed to the distal end portion of the cartridge body 1710. Another end is folded over the edge of the cartridge deck surface 1711 and includes exposed contacts configured to make electrical contact with the exposed contacts 1676 of the channel circuit 1670. Thus, when the RF cartridge 1700 is installed in the elongate channel 1602, the electrodes as well as the distal micro-chip 1740 are powered and communicate with an onboard circuit board through contact between the flexible cartridge circuit 1750, the flexible channel circuit 1670, a flexible shaft circuit and slip ring assembly.

FIG. 5 is another exploded assembly view of portions of the interchangeable shaft assembly 200 according to one aspect of this disclosure. The interchangeable shaft assembly 200 includes a firing member 220 that is supported for axial travel within a shaft spine 210. The firing member 220 includes an intermediate firing shaft portion 222 that is configured for attachment to a distal portion or bar 280. The intermediate firing shaft portion 222 may include a longitudinal slot 223 in the distal end thereof which can be configured to receive a tab 284 on the proximal end 282 of the distal bar 280. The longitudinal slot 223 and the proximal end 282 can be sized and configured to permit relative movement therebetween and can comprise a slip joint 286. The slip joint 286 can permit the intermediate firing shaft portion 222 of the firing member 220 to be moved to articulate the end effector 300 without moving, or at least substantially moving, the bar 280. Once the end effector 300 has been suitably oriented, the intermediate firing shaft portion 222 can be advanced distally until a proximal sidewall of the longitudinal slot 223 comes into contact with the tab 284 in order to advance the distal bar 280. Advancement of the distal bar 280 causes the E-beam 178 to be advanced distally to fire the staple cartridge positioned within the channel 302.

Further to the above, the shaft assembly 200 includes a clutch assembly 400 which can be configured to selectively and releasably couple the articulation driver 230 to the firing member 220. In one form, the clutch assembly 400 includes a lock collar, or sleeve 402, positioned around the firing member 220 wherein the lock sleeve 402 can be rotated between an engaged position in which the lock sleeve 402 couples the articulation drive 230 to the firing member 220 and a disengaged position in which the articulation drive 230 is not operably coupled to the firing member 220. When lock sleeve 402 is in its engaged position, distal movement of the firing member 220 can move the articulation drive 230 distally and, correspondingly, proximal movement of the firing member 220 can move the articulation drive 230 proximally. When lock sleeve 402 is in its disengaged position, movement of the firing member 220 is not transmitted to the articulation drive 230 and, as a result, the firing member 220 can move independently of the articulation drive 230.

The lock sleeve 402 can comprise a cylindrical, or an at least substantially cylindrical, body including a longitudinal aperture 403 defined therein configured to receive the firing member 220. The lock sleeve 402 can comprise diametrically-opposed, inwardly-facing lock protrusions 404 and an outwardly-facing lock member 406. The lock protrusions 404 can be configured to be selectively engaged with the firing member 220. More particularly, when the lock sleeve 402 is in its engaged position, the lock protrusions 404 are positioned within a drive notch 224 defined in the firing member 220 such that a distal pushing force and/or a proximal pulling force can be transmitted from the firing member 220 to the lock sleeve 402. When the lock sleeve 402 is in its engaged position, the second lock member 406 is received within a drive notch 232 defined in the articulation driver 230 such that the distal pushing force and/or the proximal pulling force applied to the lock sleeve 402 can be transmitted to the articulation driver 230. In effect, the firing member 220, the lock sleeve 402, and the articulation driver 230 will move together when the lock sleeve 402 is in its engaged position. On the other hand, when the lock sleeve 402 is in its disengaged position, the lock protrusions 404 may not be positioned within the drive notch 224 of the firing member 220 and, as a result, a distal pushing force and/or a proximal pulling force may not be transmitted from the firing member 220 to the lock sleeve 402. Correspondingly, the distal pushing force and/or the proximal pulling force may not be transmitted to the articulation driver 230. In such circumstances, the firing member 220 can be slid proximally and/or distally relative to the lock sleeve 402 and the proximal articulation driver 230.

The shaft assembly 200 further includes a switch drum 500 that is rotatably received on the closure tube 260. The switch drum 500 comprises a hollow shaft segment 502 that has a shaft boss 504 formed thereon for receive an outwardly protruding actuation pin 410 therein. In various circumstances, the actuation pin 410 extends through a slot 267 into a longitudinal slot 408 provided in the lock sleeve 402 to facilitate axial movement of the lock sleeve 402 when it is engaged with the articulation driver 230. A rotary torsion spring 420 is configured to engage the boss 504 on the switch drum 500 and a portion of the nozzle housing 203 as shown in FIG. 5 to apply a biasing force to the switch drum 500. The switch drum 500 can further comprise at least partially circumferential openings 506 defined therein which, referring to FIGS. 5 and 6, can be configured to receive circumferential mounts extending from the nozzle halves 202, 203 and permit relative rotation, but not translation, between the switch drum 500 and the proximal nozzle 201. The mounts also extend through openings 266 in the closure tube 260 to be seated in recesses 211 in the shaft spine 210. However, rotation of the nozzle 201 to a point where the mounts reach the end of their respective openings 506 in the switch drum 500 will result in rotation of the switch drum 500 about the shaft axis SA-SA. Rotation of the switch drum 500 will ultimately result in the rotation of the actuation pin 410 and the lock sleeve 402 between its engaged and disengaged positions. Thus, in essence, the nozzle 201 may be employed to operably engage and disengage the articulation drive system with the firing drive system in the various manners described in further detail in U.S. patent application Ser. No. 13/803,086.

The shaft assembly 200 can comprise a slip ring assembly 600 which can be configured to conduct electrical power to and/or from the end effector 300 and/or communicate signals to and/or from the end effector 300, for example. The slip ring assembly 600 can comprise a proximal connector flange 604 mounted to a chassis flange 242 extending from the chassis 240 and a distal connector flange 601 positioned within a slot defined in the nozzle halves 202, 203. The proximal connector flange 604 can comprise a first face and the distal connector flange 601 can comprise a second face which is positioned adjacent to and movable relative to the first face. The distal connector flange 601 can rotate relative to the proximal connector flange 604 about the shaft axis SA-SA. The proximal connector flange 604 can comprise a plurality of concentric, or at least substantially concentric, conductors 602 defined in the first face thereof. A connector 607 can be mounted on the proximal side of the connector flange 601 and may have a plurality of contacts, wherein each contact corresponds to and is in electrical contact with one of the conductors 602. Such an arrangement permits relative rotation between the proximal connector flange 604 and the distal connector flange 601 while maintaining electrical contact therebetween. The proximal connector flange 604 can include an electrical connector 606 which can place the conductors 602 in signal communication with a circuit board mounted to the shaft chassis 240, for example. In at least one instance, a wiring harness comprising a plurality of conductors can extend between the electrical connector 606 and the circuit board. U.S. patent application Ser. No. 13/800,067, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, filed on Mar. 13, 2013, is incorporated by reference in its entirety. U.S. patent application Ser. No. 13/800,025, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, filed on Mar. 13, 2013, is incorporated by reference in its entirety. Further details regarding slip ring assembly 600 may be found in U.S. patent application Ser. No. 13/803,086.

The shaft assembly 200 can include a proximal portion which is fixably mounted to the handle assembly 14 and a distal portion which is rotatable about a longitudinal axis. The rotatable distal shaft portion can be rotated relative to the proximal portion about the slip ring assembly 600. The distal connector flange 601 of the slip ring assembly 600 can be positioned within the rotatable distal shaft portion. Moreover, further to the above, the switch drum 500 can also be positioned within the rotatable distal shaft portion. When the rotatable distal shaft portion is rotated, the distal connector flange 601 and the switch drum 500 can be rotated synchronously with one another. In addition, the switch drum 500 can be rotated between a first position and a second position relative to the distal connector flange 601. When the switch drum 500 is in its first position, the articulation drive system may be operably disengaged from the firing drive system and, thus, the operation of the firing drive system may not articulate the end effector 300 of the shaft assembly 200. When the switch drum 500 is in its second position, the articulation drive system may be operably engaged with the firing drive system and, thus, the operation of the firing drive system may articulate the end effector 300 of the shaft assembly 200. When the switch drum 500 is moved between its first position and its second position, the switch drum 500 is moved relative to distal connector flange 601.

In various examples, the shaft assembly 200 can comprise at least one sensor configured to detect the position of the switch drum 500. The distal connector flange 601 can comprise a Hall effect sensor 605, for example, and the switch drum 500 can comprise a magnetic element, such as permanent magnet 505, for example. The Hall effect sensor 605 can be configured to detect the position of the permanent magnet 505. When the switch drum 500 is rotated between its first position and its second position, the permanent magnet 505 can move relative to the Hall effect sensor 605. In various examples, Hall effect sensor 605 can detect changes in a magnetic field created when the permanent magnet 505 is moved. The Hall effect sensor 605 can be in signal communication with a control circuit, for example. Based on the signal from the Hall effect sensor 605, a microcontroller on the control circuit can determine whether the articulation drive system is engaged with or disengaged from the firing drive system.

Referring to FIG. 10, a shaft assembly 900 is similar in many respects to the shaft assembly 200. For example, the shaft assembly 900 can be releasably coupled to the handle assembly 14. In addition, the shaft assembly 900 includes the end effector 300, for example. The shaft assembly 900 also includes the closure tube 260 which is translatable axially to transition the end effector 300 between an open configuration and a closed configuration. The shaft assembly 900 also includes the firing member 220 and the articulation driver 230 (FIG. 6). In various aspects, the shaft assembly 900 can be transitioned between an engaged articulation state (FIGS. 12, 15) wherein the articulation driver 230 and the firing member 220 are operably coupled, a disengaged articulation state (FIGS. 14, 17) wherein the articulation driver 230 (FIG. 6) and the firing member 220 are not operably coupled, and an intermediate articulation state (FIG. 13, 16) between the engaged articulation state and the disengaged articulation state.

In various aspects, distal translation of the closure tube 260 may cause the transition from the engaged articulation state to the disengaged articulation state while proximal translation of the closure tube 260 may cause the transition from the disengaged articulation state to the engaged articulation state. Various mechanisms for transitioning the shaft assembly 900 between the engaged articulation state and the disengaged articulation state are described in U.S. patent application Ser. No. 13/803,086 which is hereby incorporated by reference in its entirety.

Like the shaft assembly 200, the shaft assembly 900 can comprise a slip ring assembly 600 which can be configured to conduct electrical power to and/or from the end effector 300 and/or communicate signals to and/or from the end effector 300, for example. The slip ring assembly 600 can comprise a proximal connector flange 604 mounted between the chassis flange 242 and a washer 907, and a distal connector flange 601 positioned within a slot defined in the nozzle halves 202, 203. The distal connector flange 601 can rotate relative to the proximal connector flange 604 about a longitudinal axis 912. The proximal connector flange 604 can comprise a plurality of concentric, or at least substantially concentric, conductors 602 defined in the first face thereof. As described above in greater detail, the conductors 602, 607 maintain electrical contact therebetween while permitting relative rotation between the proximal connector flange 604 and the distal connector flange 601.

The shaft assembly 900 further includes a clutch assembly 905 including a switch collar or drum 903 that is rotatably received on the closure tube 260. An interface between the closure tube 260 and the switch drum 903 cause the switch drum 903 to be rotated in response to the axial motion of the closure tube 260. A rotary torsion spring 920 is configured to engage a boss 904 on the switch drum 903 and a portion of the nozzle housing 203 to apply a biasing force to the switch drum 903. The switch drum 903 is permitted to rotate, but not translate, between the switch drum 903 and the proximal nozzle 201. Axial translation of the closure tube 260 causes rotation of the switch drum 500 which will ultimately result in the transition of the shaft assembly 900 from the engaged articulation state to the disengaged articulation state. Thus, in essence, the closure tube 260 may be employed to operably engage and disengage the articulation drive system with the firing drive system in the various manners described in further detail in U.S. patent application Ser. No. 13/803,086.

The shaft assembly 900 can include a proximal shaft portion which is fixably mounted to the handle assembly 14 and a distal shaft portion which is rotatable about a longitudinal axis 912. The rotatable distal shaft portion can be rotated relative to the proximal shaft portion about the slip ring assembly 600. The distal connector flange 601 of the slip ring assembly 600 can be positioned within the rotatable distal shaft portion. Moreover, further to the above, the switch drum 903 can also be positioned within the rotatable distal shaft portion. When the rotatable distal shaft portion is rotated, the distal connector flange 601, the closure tube 260, the switch drum 903, and the nozzle 201 can be rotated synchronously with one another, as outlined in the table 909 of FIG. 11. The chassis flange 242, the proximal connector flange 604, and the washer 907 are not rotated during rotation of the distal shaft portion.

Further to the above, the switch drum 903 can be rotated between a first position (FIGS. 12, 15), a second position (FIGS. 13, 16), and a third position (FIGS. 14, 17) relative to chassis flange 242, the proximal connector flange 604, the washer 907, the closure tube 260, and the distal connector flange 601. The axial translation of the closure tube 260 can effect the rotation of the switch drum 903 between the first position, second position, and third position. When the switch drum 903 is in its first position, the articulation drive system may be operably engaged with the firing drive system and, thus, the operation of the firing drive system may articulate the end effector 300 of the shaft assembly 900. The first position defines an articulation engaged state of the shaft assembly 900. When the switch drum 903 is in its third position, the articulation drive system may be operably disengaged from the firing drive system and, thus, the operation of the firing drive system may not articulate the end effector 300 of the shaft assembly 900. The third position defines an articulation disengaged state of the shaft assembly 900. Furthermore, the switch drum 903 can be moved to from its first position or third position to its second position. The second position is an intermediate position defined between the first position and the third position. The second position represents a transitory state between the articulation engaged and articulation disengaged states.

In various instances, the shaft assembly 900 can comprise at least one sensor configured to detect the position of the switch drum 903. The distal connector flange 601 can comprise a printed circuit board (PCB) 908 that includes a Hall effect sensor 910, for example, and the switch drum 903 can comprise a magnetic element, such as permanent magnet 911, for example. The Hall effect sensor 910 can be configured to detect the position of the permanent magnet 911. When the switch drum 903 is rotated between its first position, its second position, and its third position, the permanent magnet 911 moves relative to the Hall effect sensor 910. In various instances, Hall effect sensor 910 can detect changes in a magnetic field created when the permanent magnet 911 is moved. The Hall effect sensor 910 can vary its output signal in response to the change in the magnetic field caused by the movement of the permanent magnet 911. In various examples, the output signal can be a voltage output signal or a current output signal.

Referring to FIG. 18, a shaft assembly 1000 is similar in many respects to the shaft assemblies 200, 900. In some examples, the shaft assembly 1000 is releasably coupled to the housing 12 (FIG. 1). Several components of the shaft assembly 1000 that are similar to components shown in connection with the shaft assembly 200 and/or the shaft assembly 900 are removed to better illustrate components that are unique to the shaft assembly 1000. For example, the shaft assembly 1000, like the shaft assemblies 200, 900, includes a slip ring assembly which is not shown in FIG. 18.

The shaft assembly 1000 includes a proximal shaft portion which is fixably mounted to the handle assembly 14 and a distal shaft portion which is rotatable about a longitudinal axis 1012. The rotatable distal shaft portion can be rotated relative to the proximal shaft portion about the slip ring assembly. A clutch assembly 1002 includes a switch collar or drum 1003, which is similar in many respects to the switch drum 903 (FIG. 10), can also be positioned within the rotatable distal shaft portion. When the rotatable distal shaft portion is rotated, the closure tube 260, the switch drum 1003, and the nozzle 201 can be rotated synchronously with one another.

Further to the above, the switch drum 1003 can be rotated relative to the closure tube 260. The axial translation of the closure tube 260 can effect the rotation of the switch drum 1003. Like the switch drum 903, the switch drum 1003 can be rotated in response to the axial translation of the closure tube 260, which transitions the shaft assembly 1000 between the articulation engaged state and the articulation disengaged state. As discussed above, in the articulation engaged state, the articulation drive system is operably engaged with the firing drive system and, thus, the operation of the firing drive system may articulate the end effector 300 of the shaft assembly 1000. In the articulation disengaged state, the articulation drive system may be operably disengaged from the firing drive system and, thus, the operation of the firing drive system may not articulate the end effector 300 of the shaft assembly 1000.

Referring to FIG. 18, the shaft assembly 1000 includes a rotation detection assembly 1004 configured to determine the rotational position of one or more components of the distal shaft portion of the shaft assembly 1000 as defined by a degree and a direction of rotation. The rotation detection assembly 1004 includes a first Hall effect sensor 1005, a second Hall effect sensor 1006, a first permanent magnet 1007, a second permanent magnet 1008, and a control circuit 1010 in electrical communication with the Hall effect sensors 1005, 1006.

Referring to FIG. 19, the Hall effect sensors 1005, 1006 are positioned on the same side of a support portion 1011. The Hall effect sensors 1005, 1006 are positioned toward opposite ends of the support portion 1011. The control circuit 1010 is at least partially housed in the nozzle 201. In some examples, the Hall effect sensors 1005, 1006 are housed in the nozzle 201 but the control circuit 1010 is housed elsewhere in the surgical instrument 10 (FIG. 1) such as, for example, in the housing 12. In the embodiment of FIG. 18, the Hall effect sensors 1005, 1006 are positioned on opposite sides of a plane transecting the control circuit 1010, the support portion 1011, and the closure tube 260. The Hall effect sensors 1005, 1006 are equidistant, or at least substantially equidistant, from the first permanent magnet 1007 at its starting position along the positive Y-axis, as illustrated in FIG. 20.

As discussed above in connection with the table 909 of FIG. 11, the closure tube 260, the switch drum 1003, and the nozzle 201 are rotated synchronously with one another during a user-controlled shaft rotation but only the switch drum 1003 is rotated during a change in the articulation engagement state. The rotation detection assembly 1004 may track the user-controlled shaft rotation by tracking the rotation of the nozzle 201, for example. In addition, the rotation detection assembly 1004 may track the articulation engagement state of the shaft assembly 1000 by tracking the rotation of the switch drum 1003. The control circuit 1010 is configured to determine of the rotational position of the nozzle 201 and/or the switch drum 1003 as defined by a degree and direction of rotation.

Referring to FIGS. 18-21, the first permanent magnet 1007 is attached to the nozzle 201. Rotation of the nozzle 201 causes the first permanent magnet 1007 to rotate about a longitudinal axis 1012 that extends longitudinally through the closure tube 260. Every rotational position of the first permanent magnet 1007 can be determined based on the distances (a) and (b) between the first permanent magnet 1007 and the Hall effect sensors 1005, 1006, respectively. Although one Hall effect sensor can be employed to determine the degree of rotation of the distal shaft portion of the shaft assembly 1000, the use of two Hall effect sensors can further provide information as to the direction of rotation of the distal shaft portion of the shaft assembly 1000. The intensity of the magnetic field of the first permanent magnet 1007 as detected by the Hall effect sensor 1005 corresponds to the distance (a) between the first permanent magnet 1007 and the Hall effect sensor 1005, and the intensity of the magnetic field of the first permanent magnet 1007 as detected by the Hall effect sensor 1006 corresponds to the distance (b) between the first permanent magnet 1007 and the Hall effect sensor 1006. The output signals of the Hall effect sensors 1005, 1006 correspond to the intensity of the magnetic field of the first permanent magnet 1007 as detected by the Hall effect sensors 1005, 1006.

Accordingly, a correlation exists between the output signals of the Hall effect sensors 1005, 1006 and their respective distances (a), (b) from the first permanent magnet 1007. The control circuit 1010 can be configured to determine the rotational position of the distal shaft portion of the shaft assembly 1000 in a user-controlled shaft rotation based on the output signals of the Hall effect sensors 1005, 1006. In various examples, a ratio of the output signal of the Hall effect sensor 1005 and the Hall effect sensor 1006 corresponds to the rotational position of the distal shaft portion of the shaft assembly 1000. The output signal ratio will have a value that is unique to each rotational position of the distal shaft portion of the shaft assembly 1000 except for the ratio at the starting position along the positive Y-axis and the ratio at the position along the negative Y-axis which are both equal to one. At each of the rotational positions at 0° and 180°, the distances (a) and (b) are the same, or at least substantially the same which causes the output signal ratio to be equal to one.

To differentiate between the rotational positions at 0° and 180°, the magnitude of the output signal of one of the Hall effect sensors 1005, 1006 can be considered. Since the distances (a) and (b) at the position at 180°, along the negative Y-axis, is greater than the distances (a) and (b) at the position at 0°, along the positive Y-axis, a output signal ratio equal to one and a output signal greater than a predetermined voltage threshold can indicate that the rotational position of the distal shaft portion of the shaft assembly 1000 is at 180° along the negative Y-axis. However, an output signal ratio equal to one and an output signal less than the predetermined voltage threshold can indicate that the rotational position of the distal shaft portion of the shaft assembly 1000 is at 0° along the positive Y-axis. Furthermore, any two opposing rotational positions have inverse output signal ratios of one another. For example, the rotational position at 90° has an inverse output signal ratio of the rotational position at 270°.

In some examples, the control circuit 1010 may employ an equation and/or a look-up table to determine the rotational position of the distal shaft portion of the shaft assembly 1000 based on the output signals of the Hall effect sensors 1005, 1006. The look-up table may list rotational positions of the distal shaft portion of the shaft assembly 1000 and corresponding output signal ratios of the output signals of the Hall effect sensors 1005, 1006.

Other algorithms for determining the rotational position of the distal shaft portion of the shaft assembly 1000 based on the output signals of the Hall effect sensors 1005, 1006 are contemplated by the present disclosure. In some examples, the difference between the output signals of the Hall effect sensors 1005, 1006 may correlate to the rotational position of the distal shaft portion of the shaft assembly 1000. The control circuit 1010 can be configured to subtract the output signal of the Hall effect sensor 1005 from the output signal of the Hall effect sensor 1006, and determine the rotational position of the distal shaft portion of the shaft assembly 1000 based on the calculated voltage difference. The control circuit 1010 may employ a look-up table, for example, that lists the rotational positions of the distal shaft portion of the shaft assembly 1000 and their corresponding voltage differences. As described above, differentiating between the rotational positions at 0° and 180° can be performed by further employing a predetermined voltage threshold.

Alternatively, in some examples, the rotational position of the distal shaft portion of the shaft assembly 1000 can be determined from a look-up table that stores rotational positions of the distal shaft portion of the shaft assembly 1000 in a first column, corresponding output signals of the Hall effect sensor 1005 in a second column, and corresponding output signals 1006 in a third columns. The control circuit 1010 can be configured to determine a present rotational position of the distal shaft portion of the shaft assembly 1000 by looking up a value from the first column that corresponds to values from the second and third columns that match present output signals of the Hall effect sensors 1005, 1006.

Referring to FIGS. 20, 21, the rotational position of the first permanent magnet 1007 is at an angle θ₁ in a counter clockwise direction. A control circuit 1010 receiving output signals of the Hall effect sensors 1005, 1006 can determine the rotational position of the distal shaft portion of the shaft assembly 1000 through a look-up table that includes rotational positions of the distal shaft portion of the shaft assembly 1000 and corresponding values of the output signals, the ratios of the output signals, and/or the differences between the output signals. In some examples, the control circuit 1010 is coupled to a display 93 (FIG. 1) that is configured to display the rotational position of the distal shaft portion of the shaft assembly 1000. Although the above-described examples employ look-up tables, it is understood that other mechanisms can be employed to achieve the same results such as, for example, a memory unit 1122 (FIG. 22), which can be accessed by the control circuit 1010.

In addition to rotating with the distal shaft portion of the shaft assembly 1000, the switch drum 1003 can be rotated relative to the shaft assembly 1000 about the longitudinal axis 1012 in response to the axial translation of the closure tube 260. The switch drum 1003 is rotated from a first rotational position, as illustrated in FIG. 20, to a second rotational position, as illustrated in FIG. 21. While the switch drum 1003 is in the first rotational position, the shaft assembly 1000 is in the articulation engaged state. While the switch drum 1003 is in the second rotational position, the shaft assembly 1000 is in the articulation disengaged state. Since the permanent magnet 1008 is attached to the switch drum 1003, the rotational position of the permanent magnet 1008 can be indicative of the articulation state of the shaft assembly 1000.

Since the permanent magnet 1008 and the switch drum 1003 rotate with the shaft assembly 1000, two Hall effect sensors are needed to discern the relative rotational motion between the switch drum 1003 and the shaft assembly 1000 in order to determine the articulation state of the shaft assembly 1000. The first rotational position of the switch drum 1003, which corresponds to the articulation engaged state, and the second position, which corresponds to the articulation disengaged state, will vary depending on the rotational position of the distal shaft portion of the shaft assembly 1000.

The control circuit 1010 is configured to determine an articulation state of the shaft assembly 1000 by determining the rotational position of the switch drum 1003 relative to the rotational position of the distal shaft portion of the shaft assembly 1000. Said another way, the control circuit 1010 is configured to determine an articulation state of the shaft assembly 1000 by determining the rotational position of the permanent magnet 1008 relative to the rotational position of the permanent magnet 1007. The permanent magnets 1007 and 1008 comprise opposite orientations to permit the Hall effect sensors 1005, 1006 to distinguish therebetween. In the embodiment illustrated in FIG. 18, the first permanent magnet 1007 comprises a negative orientation while the second permanent magnet 1008 comprises a negative orientation.

As described above in connection with the first permanent magnet 1007, the degree and direction of rotation of the second permanent magnet 1008 can be determined based on the output signals of the Hall effect sensors 1005, 1006. The intensity of the magnetic field of the second permanent magnet 1008 as detected by the Hall effect sensor 1005 corresponds to the distance (c) between the second permanent magnet 1008 and the Hall effect sensor 1005, and the intensity of the magnetic field of the second permanent magnet 1008 as detected by the Hall effect sensor 1006 corresponds to the distance (d) between the second permanent magnet 1008 and the Hall effect sensor 1006. The output signals of the Hall effect sensors 1005, 1006 correspond to the intensity of the magnetic field of the second permanent magnet 1008 as detected by the Hall effect sensors 1005, 1006. Accordingly, a correlation exists between the output signals of the Hall effect sensors 1005, 1006 and their respective distances (c), (d) from the second permanent magnet 1008.

The control circuit 1010 can be configured to determine the rotational position of the switch drum 1003 based on the output signals of the Hall effect sensors 1005, 1006, as described above in connection with the rotational position of the shaft assembly 1000. As illustrated in FIGS. 20, 21, the rotational position of the permanent magnet 1008 is at an angle β₁ in a counter clockwise direction. A control circuit 1010 receiving output signals of the Hall effect sensors 1005, 1006 can determine the rotational position of the switch drum 1003 through a look-up table that includes rotational positions of the switch drum 1003 and corresponding values of the output signals, the ratios of the output signals, and/or the differences between the output signals, as described above in connection with determining the rotational position of the distal shaft portion of the shaft assembly 1000.

To determine the articulation state of the shaft assembly 1000, the control circuit 1010 is configured to detect the relative motion between the shaft assembly 1000 and the switch drum 1003. Said another way, the control circuit 1010 is configured to detect the relative motion between the first permanent magnet 1007, which is attached to the nozzle 201, and the permanent magnet 1008, which is attached to the switch drum 1003. In the example of FIGS. 20, 21, the rotational position of the distal shaft portion of the shaft assembly 1000 remains at the angle θ₁. The rotational position of the switch drum 1003, however, changed from the angle β1 to the angle β2 indicating a change in the articulation state of the shaft assembly 1000. Accordingly, the rotational position of the permanent magnet 1008 has moved relative to the rotational position of the first permanent magnet 1007 as a result of the rotation of the switch drum 1003 which causes the change in the articulation state of the shaft assembly 1000.

In some examples, as described in greater detail above, a switch drum such as, for example, the switch drum 1003 is movable between a first rotational position, corresponding to an articulation engaged state, and a second rotational position, corresponding to an articulation disengage state. At the first rotational position, a first angle Γ1 (FIG. 20) is measured between the first permanent magnet 1007 and the permanent magnet 1008 regardless of the rotational position of the distal shaft portion of the shaft assembly 1000. At the second rotational position, a first angle Γ2 (FIG. 21) different from the first angle Γ1 is measured the first permanent magnet 1007 and the permanent magnet 1008.

Accordingly, the control circuit 1010 can be configured to determine the articulation state of the shaft assembly 1000 by determining the angle between the first permanent magnet 1007 and the permanent magnet 1008 and comparing such angle to a predetermined value. In various examples, the angle between the first permanent magnet 1007 and the permanent magnet 1008 by subtracting the rotational position of the first permanent magnet 1007 from the rotational position of the permanent magnet 1008. In some examples, the control circuit 1010 is coupled to a display 93 (FIG. 1) that is configured to display the detected articulation state of the shaft assembly 1000.

In some examples, the control circuit 1010 is configured to determine a change in the articulation state of the shaft assembly 1000 by detecting a change in the rotational position of the clutch assembly 1002 occurring without a corresponding change in the rotational position of the distal shaft portion of the shaft assembly 1000. Said another way, in such examples, a change in the rotational position of the second permanent magnet 1008 not accompanied by a change in the rotational position of the first permanent magnet 1007 can be interpreted by the control circuit 1010 as a change in the articulation state of the shaft assembly 1000. This is because the shaft assembly 1000 and the clutch assembly 1002 rotate synchronously during a user-controlled rotation of the distal shaft portion of the shaft assembly 1000 but only the clutch assembly 1002 is rotated during an articulation state of the shaft assembly 1000.

FIG. 22 depicts an example of the control circuit 1010. The control circuit 1010 may include a controller 1020 (“microcontroller”) which may include a processor 1021 (“microprocessor”) and one or more computer readable mediums or memory 1022 units (“memory”). In certain instances, the memory 1022 may store various program instructions, which when executed may cause the processor 1021 to perform a plurality of functions and/or calculations described herein. In certain instances, the memory 1022 may be coupled to the processor 1021, for example. A power source 98 (FIG. 2) can be configured to supply power to the controller 1020. In certain instances, the controller 1020 can be operably coupled to the feedback indicator or display 93.

In various examples, the control circuit 1010 may store a current articulation state of the shaft assembly 1000. Upon detecting a change in the articulation state of the shaft assembly 1000, the control circuit 1010 may update the stored articulation state and display the new articulation state on the display 93.

Other types of sensors can be employed to determine an articulation state of a shaft assembly based on the relative the rotational positions of the distal shaft portion of a shaft assembly and its clutch assembly. In some arrangements, optical sensors, electromagnetic sensors, mechanical sealed contact switches, or any combinations thereof can be employed to determine an articulation state of a shaft assembly based on the relative the rotational positions of the distal shaft portion of a shaft assembly and its clutch assembly. FIG. 23 depicts a partial perspective view of a shaft assembly 1100 that includes a clutch assembly 1102. A rotation detection assembly 1104 of the shaft assembly 1100 employs optical sensors 1105, 1106 to determine an articulation state of the shaft assembly 1100 based on the relative the rotational positions of the distal shaft portion of the shaft assembly 1100 and the clutch assembly 1102.

The rotation detection assembly 1104 includes a control circuit 1110 configured to track the user-controlled shaft rotation by tracking the rotational position of a cylindrical portion 1107 of the nozzle 201, for example. In addition, the control circuit 1110 is further configured to track the rotational position of the clutch assembly 1102 by tracking the rotation of a cylindrical portion 1108 of a switch drum 1103 of the clutch assembly 1102. The articulation state of the shaft assembly 1100 can be determined by the control circuit 1110 based on the relative the rotational positions of the cylindrical portions 1107, 1108.

The shaft assembly 1100 is similar in many respects to the shaft assembly 1000. For example, the shaft assembly 1100 includes the nozzle 201 and the closure tube 260. Axial motion of the closure tube 260 along a longitudinal axis 1112 causes a clutch assembly 1102 to be rotated about the longitudinal axis 1112 transitioning the shaft assembly 1100 between an articulation engaged state at a first rotational position of a switch drum 1103, and an articulation disengaged state at a second rotational position of the switch drum 1103. As discussed above, in the articulation engaged state, the articulation drive system is operably engaged with the firing drive system and, thus, the operation of the firing drive system may articulate the end effector 300 of the shaft assembly 1100. In the articulation disengaged state, the articulation drive system may be operably disengaged from the firing drive system and, thus, the operation of the firing drive system may not articulate the end effector 300 of the shaft assembly 1100.

Referring to FIGS. 23, 24, the rotation detection assembly 1104 includes a support ledge 1111 extending between the cylindrical portions 1107, 1108. The optical sensors 1105, 1106 are positioned on opposite sides of the support ledge 1111 such that the optical sensor 1105 faces or is directed toward an inner surface of the cylindrical portion 1107. The optical sensor 1106 faces or is directed toward an outer surface of the cylindrical portion 1108. Although the example of FIG. 23 depicts the cylindrical portion 1107 in an outer position relative to the cylindrical portion 1108. In some examples, however, the cylindrical portion 1107 can be in an inner position relative to the cylindrical portion 1108.

As illustrated in FIG. 23, the cylindrical portions 1107, 1108 are concentric and rotatable about a longitudinal axis 1112. The cylindrical portion 1107 is attached to the nozzle 201 and includes a number of longitudinal slits 1125 each extending longitudinally in parallel, or at least substantially in parallel, with the longitudinal axis 1112. The slits 1125 are formed in the cylindrical portion 1107 by making longitudinal thorough cuts that are spaced apart at predetermined distances. In some examples, the predetermined distances can be the same, or at least substantially the same. Alternatively, in other examples, the predetermined distances can be different.

In FIG. 24, the cylindrical portion 1107 is removed to better expose other components of the shaft assembly 1100. The cylindrical portion 1108 extends proximally from the switch drum 1103 and includes a number of longitudinal slits 1126 each extending longitudinally in parallel, or at least substantially in parallel, with the longitudinal axis 1112. The slits 1126 are formed in the cylindrical portion 1108 by making longitudinal thorough cuts that are spaced apart at predetermined distances.

In some examples, the predetermined distances can be the same, or at least substantially the same. Alternatively, in other examples, the predetermined distances can be different. In some examples, the slits 1125, 1126 are equally spaced apart. Alternatively, the slits 1125 can be spaced apart at predetermined distances that are different from the predetermined distances of the slits 1126.

The optical sensors 1105, 1106 convert light rays into output signals indicative of the physical quantity of light detected. The control circuit 1110 is configured to determine the articulation state of the shaft assembly 1100 based on the output signals of the optical sensors 1105, 1106. Rotation of the cylindrical portions 1107, 1108 cause changes in the incident light detected by the optical sensors 1105, 1106, respectively. When changes in the incident light occur, the optical sensors 1105, 1106 change their output signals in a manner corresponding to the changes in the incident light. The output signals of the optical sensors 1105, 1106 can be output voltage, output current, or output resistance.

As described above in connection with the control circuit 1010, the control circuit 1110 may employ various algorithms, equations, and/or look-up tables to determine the articulation state of the shaft assembly 1100 based on the output signals of the optical sensors 1105, 1106 and/or derivatives thereof. The control circuit 1110 can be configured to use the output signal of the optical sensor 1105 to count the number of slits 1125 passing relative to the optical sensor 1105 during the rotation of the cylindrical portion 1107. The control circuit 1110 can also be configured to use the output signal of the optical sensor 1106 to count the number of slits 1126 passing relative to the optical sensor 1106 during the rotation of the cylindrical portion 1108. During a user-controlled rotation of the distal shaft portion of the shaft assembly 1100, the shaft assembly 1100 and the clutch assembly 1102 are synchronously rotated. Accordingly, the counted number of slits 1125 and the counted number of slits 1126 remain at a constant, or substantially constant, slit ratio as long as the slits 1125 are equally spaced apart and the slits 1126 are also equally spaced apart. During a change in the articulation state of the shaft assembly 1100, however, the clutch assembly 1102 is rotated relative to the shaft assembly 1100 causing the slit ratio to be changed. The control circuit 1110 can be configured to track the slit ration and detect a change in the articulation state of the shaft assembly 1100 in response to a change in the slit ratio.

In some examples, the control circuit 1110 is configured to determine a change in the articulation state of the shaft assembly 1100 by detecting a change in the rotational position of the clutch assembly 1102 occurring without a corresponding change in the rotational position of the distal shaft portion of the shaft assembly 1100. Said another way, a change in the rotational position of the cylindrical portion 1108 not accompanied by a change in the rotational position of the cylindrical portion 1107 can be interpreted by the control circuit 1110 as a change in the articulation state of the shaft assembly 1100. Said another way, a change in the output signal of optical sensor 1106 not accompanied by a change in the output signal of the optical sensor 1105 can be interpreted by the control circuit 1110 as a change in the articulation state of the shaft assembly 1100. This is because the shaft assembly 1100 and the clutch assembly 1102 rotate synchronously during a user-controlled rotation of the distal shaft portion of the shaft assembly 1100 but only the clutch assembly 1102 is rotated during an articulation state of the shaft assembly 1000.

FIG. 25 depicts an example of the control circuit 1110. The control circuit 1110 may include a controller 1020 (“microcontroller”) which may include a processor 1021 (“microprocessor”) and one or more computer readable mediums or memory 1022 units (“memory”). In certain instances, the memory 1022 may store various program instructions, which when executed may cause the processor 1021 to perform a plurality of functions and/or calculations described herein. In certain instances, the memory 1022 may be coupled to the processor 1021, for example. A power source 98 (FIG. 2) can be configured to supply power to the controller 1020. In certain instances, the controller 1020 can be operably coupled to the feedback indicator or display 93.

In various examples, the control circuit 1110 may store a current articulation state of the shaft assembly 1100. Upon detecting a change in the articulation state of the shaft assembly 1100, the control circuit 1110 may update the stored articulation state and display the new articulation state on the display 93.

In some examples, one or both of the optical sensors 1105, 1106 can be a through-beam sensor. Through-beam sensors employ two separate components, a transmitter and a receiver, which are placed opposite to each other. The transmitter projects a light beam onto the receiver. An interruption of the light beam is interpreted as a switch signal by the receiver. In examples where the optical sensors 1105, 1106 are through-beam sensors, a transmitter and a receiver may be positioned on opposite sides of each of the cylindrical portions 1107, 1108. The light beams of transmitters of the optical sensors 1105, 1106 may pass through the slits 1125, 1126, respectively, to the receivers. Rotation of the cylindrical portions 1107, 1108 may interrupt the light beams. Such interruptions can be tracked by the control circuit 1110 to determine the rotational positions of the distal shaft portion of the shaft assembly 1100 and the switch drum 1103.

In other examples, the optical sensors 1105, 1106 can be retro-reflective Sensors where the transmitters and receivers are on the same side of a cylindrical portion. The emitted light beam is directed back to the receiver through a reflector. In other examples, the optical sensors 1105, 1106 can be diffuse reflection sensors where both transmitter and receiver are on the same side of a cylindrical portion. The transmitted light is reflected by the cylindrical portion to be detected.

Since clutch assemblies are synchronously rotated with their respective shaft assemblies, detecting a change in the articulation state necessitates tracking the rotation of the clutch assembly relative to the shaft assembly. An alternative approach, however, may involve tracking an axial translation of the clutch assembly that is caused to occur during a change in the articulation state in addition to the rotation. A switch plate my include ramps or tabs that interface with the switch drum of the clutch assembly causing the switch drum to be lifted or translated axially as the switch drum is rotated relative to the shaft assembly during a change in the articulation state. The axial motion of the switch drum can be detected by a position sensor, for example. A control circuit can be configured to interpret an axial translation of the switch drum as a change in the articulation state of the shaft assembly. The switch drum can be spring biased against the switch plate to return the switch drum to its starting position during a rotation in the opposite direction. The switch plate may include slits configured to receive ribs or tabs on the nozzle to ensure rotational alignment of the switch plate and the nozzle.

In certain instances, an axial translation of the switch drum, during the rotation of the clutch assembly, can also be achieved by forming external threads on an outer surface of the switch drum that interface with internal threads of a switch nut. Rotational movement of the switch drum causes linear movements of the switch nut. A suitable sensor can be configured to detect the position of the switch nut. A control circuit can be configured to determine the articulation state based on the position of the switch nut.

In certain instances, the detection of the articulation state of a shaft assembly can be achieved by attaching a conductive leaf spring to the outer diameter of the switch drum. The conductive leaf spring detects the rotation of the clutch assembly which indicates a change in the articulation state. The conductive leaf spring can be a component of a circuit transitionable between an open configuration when the clutch assembly is in an articulation engaged state, and a closed configuration when the clutch assembly is in an articulation disengaged state. Alternatively, the conductive leaf spring can be a component of a circuit transitionable between an open configuration when the clutch assembly is in an articulation disengaged state, and a closed configuration when the clutch assembly is in an articulation engaged state.

In certain instances, a barcode scanner component can be employed to detect a change in the articulation state of a shaft assembly. Barcode scanners operate by sensing the amount of black color on a white background, for example. The switch drum of the clutch assembly and the nozzle can be configured to present the bar code scanner with a first pattern in an articulation engaged state and a second pattern, different from the first pattern, in an articulation disengaged state. Rotation of the clutch assembly relative to the nozzle can cause a transition from the first pattern to the second pattern.

In a general sense, those skilled in the art will recognize that the various aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, as used herein “electrical circuitry” includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a processor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). Those having skill in the art will recognize that the subject matter described herein may be implemented in an analog or digital fashion or some combination thereof.

The foregoing detailed description has set forth various aspects of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one aspect, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. Those skilled in the art will recognize, however, that some aspects of the aspects disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure.

In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative aspect of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.).

In summary, numerous benefits have been described which result from employing the concepts described herein. The foregoing description of the one or more aspects has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The one or more aspects were chosen and described in order to illustrate principles and practical application to thereby enable one of ordinary skill in the art to utilize the various aspects and with various modifications as are suited to the particular use contemplated. It is intended that the claims submitted herewith define the overall scope.

Various aspects of the subject matter described herein are set out in the following numbered examples:

Example 1

A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly comprises a proximal shaft portion, a distal shaft portion, and a control circuit. The proximal shaft portion comprises a first sensor and a second sensor. The distal shaft portion is rotatable about the longitudinal axis and relative to the proximal shaft portion. The distal shaft portion comprises a housing, a first magnet rotatable with the housing, a clutch assembly, and a second magnet rotatable with the clutch assembly. The clutch assembly is rotatable relative to the housing to transition the shaft assembly between an articulation engaged state and an articulation disengaged state. The control circuit is configured to detect a transition from the articulation engaged state to the articulation disengaged state based on output signals from the first sensor and the second sensor.

Example 2

The shaft assembly of Example 1, wherein the first sensor and the second sensor are Hall effect sensors.

Example 3

The shaft assembly of one or more of Example 1 through Example 2, wherein the output signals of the first and second sensors define a rotational position of the shaft assembly.

Example 4

The shaft assembly of one or more of Example 1 through Example 3, wherein the first magnet and the second magnet comprise opposite orientations.

Example 5

The shaft assembly of one or more of Example 1 through Example 4, wherein the output signals of the first and second sensors define a rotational position of the clutch assembly.

Example 6

The shaft assembly of one or more of Example 1 through Example 5, wherein the shaft assembly further comprises an end effector extending therefrom.

Example 7

A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly comprises a proximal shaft portion, a distal shaft portion, and a control circuit. The proximal shaft portion comprises a first sensor and a second sensor. The distal shaft portion is rotatable about the longitudinal axis and relative to the proximal shaft portion. The distal shaft portion comprises a housing, a first magnet rotatable with the housing, a clutch assembly, and a second magnet rotatable with the clutch assembly. The clutch assembly is rotatable relative to the housing to transition the shaft assembly between an articulation engaged state and an articulation disengaged state. The control circuit is configured to detect a transition from the articulation engaged state to the articulation disengaged state based on relative rotational positions of the distal shaft portion of the shaft assembly and the clutch assembly.

Example 8

The shaft assembly of Example 7, wherein the first sensor and the second sensor are Hall effect sensors.

Example 9

The shaft assembly of one or more of Example 7 through Example 8, wherein the output signals of the first and second sensors define the rotational positions of the shaft assembly.

Example 10

The shaft assembly of one or more of Example 7 through Example 9, wherein output signals of the first and second sensors define the rotational positions of the clutch assembly.

Example 11

The shaft assembly of one or more of Example 7 through Example 10, wherein the first magnet and the second magnet comprise opposite orientations.

Example 12

The shaft assembly of one or more of Example 7 through Example 11, wherein the shaft assembly further comprises an end effector extending therefrom.

Example 13

A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly comprises a proximal shaft portion, a distal shaft portion, and a control circuit. The proximal shaft portion comprises a first sensor configured to generate a first output signal and a second sensor configured to generate a second output signal. The distal shaft portion comprises a clutch assembly rotatable with the distal shaft portion about the longitudinal axis and relative to the proximal shaft portion, wherein the rotation of the clutch assembly with the distal shaft portion changes the first output signal. The clutch assembly is further rotatable relative to the distal shaft portion to transition the shaft assembly between an articulation engaged state and an articulation disengaged state, wherein the rotation of the clutch assembly relative to the distal shaft portion changes the second output signal. The control circuit is in electrical communication with the first sensor and the second sensor, wherein the control circuit is configured to detect a change in the second output signal occurring without a corresponding change in the first output signal, and wherein the detected change indicates a transition between the articulation engaged state and the articulation disengaged state.

Example 14

The shaft assembly of Example 13, wherein the first sensor and the sensor are optical sensors.

Example 15

The shaft assembly of one or more of Example 13 through Example 14, wherein the distal shaft portion comprises a first cylindrical portion including first slits, wherein the first slits are passed over the first sensor during the rotation of the distal shaft portion, and wherein the passing of the first slits over the first sensor changes the first output signal.

Example 16

The shaft assembly of one or more of Example 13 through Example 15, wherein the clutch assembly comprises a second cylindrical portion including second slits, wherein the second slits are passed over the second sensor during the rotation of the clutch assembly relative to the distal shaft portion, and wherein the passing of the second slits over the second sensor changes the second output signal.

Example 17

The shaft assembly of one or more of Example 13 through Example 16, wherein the first sensor and the second sensor are disposed on opposite sides of a support member.

Example 18

The shaft assembly of one or more of Example 13 through Example 17, wherein the support member extends between the first cylindrical portion and the second cylindrical portion.

Example 19

The shaft assembly of one or more of Example 13 through Example 18, wherein the first sensor is directed toward an inner surface of the first cylindrical portion.

Example 20

The shaft assembly of one or more of Example 13 through Example 19, wherein the second sensor is directed toward an outer surface of the second cylindrical portion.

Example 21

A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly. The shaft assembly comprises a proximal shaft portion and a distal shaft portion. The proximal shaft portion comprises a first sensor configured to generate a first output signal and a second sensor configured to generate a second output signal. The distal shaft portion comprises a switching component rotatable with the distal shaft portion about the longitudinal axis and relative to the proximal shaft portion, wherein the switching component is further rotatable relative to the distal shaft portion to transition the shaft assembly between an articulation engaged state and an articulation disengaged state. Rotation of the distal shaft portion relative to the proximal shaft portion is determined based on the first output signal, and rotation of the switching component relative to the distal shaft portion is determined based on a combination of the first output signal and the second output signal. 

1. A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly, wherein the shaft assembly comprises: a proximal shaft portion, comprising: a first sensor; and a second sensor; a distal shaft portion rotatable about the longitudinal axis and relative to the proximal shaft portion, wherein the distal shaft portion comprises: a housing; a first magnet rotatable with the housing; a clutch assembly rotatable relative to the housing to transition the shaft assembly between an articulation engaged state and an articulation disengaged state; and a second magnet rotatable with the clutch assembly; and a control circuit configured to detect a transition from the articulation engaged state to the articulation disengaged state based on output signals from the first sensor and the second sensor.
 2. The shaft assembly of claim 1, wherein the first sensor and the second sensor are Hall effect sensors.
 3. The shaft assembly of claim 1, wherein the output signals of the first and second sensors define a rotational position of the shaft assembly.
 4. The shaft assembly of claim 1, wherein the first magnet and the second magnet comprise opposite orientations.
 5. The shaft assembly of claim 1, wherein the output signals of the first and second sensors define a rotational position of the clutch assembly.
 6. The shaft assembly of claim 1, wherein the shaft assembly further comprises an end effector extending therefrom.
 7. A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly, wherein the shaft assembly comprises: a proximal shaft portion, comprising: a first sensor; and a second sensor; a distal shaft portion rotatable about the longitudinal axis and relative to the proximal shaft portion, wherein the distal shaft portion comprises: a housing; a first magnet rotatable with the housing; a clutch assembly rotatable relative to the housing to transition the shaft assembly between an articulation engaged state and an articulation disengaged state; and a second magnet rotatable with the clutch assembly; and a control circuit configured to detect a transition from the articulation engaged state to the articulation disengaged state based on relative rotational positions of the distal shaft portion of the shaft assembly and the clutch assembly.
 8. The shaft assembly of claim 7, wherein the first sensor and the second sensor are Hall effect sensors.
 9. The shaft assembly of claim 7, wherein output signals of the first and second sensors define the rotational positions of the shaft assembly.
 10. The shaft assembly of claim 7, wherein output signals of the first and second sensors define the rotational positions of the clutch assembly.
 11. The shaft assembly of claim 7, wherein the first magnet and the second magnet comprise opposite orientations.
 12. The shaft assembly of claim 7, wherein the shaft assembly further comprises an end effector extending therefrom.
 13. A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly, wherein the shaft assembly comprises: a proximal shaft portion, comprising: a first sensor configured to generate a first output signal; and a second sensor configured to generate a second output signal; a distal shaft portion comprising a clutch assembly rotatable with the distal shaft portion about the longitudinal axis and relative to the proximal shaft portion, wherein the clutch assembly is further rotatable relative to the distal shaft portion to transition the shaft assembly between an articulation engaged state and an articulation disengaged state, wherein the rotation of clutch assembly with the distal shaft portion changes the first output signal, and wherein the rotation of the clutch assembly relative to the distal shaft portion changes the second output signal; and a control circuit in electrical communication with the first sensor and the second sensor, wherein the control circuit is configured to detect a change in the second output signal occurring without a corresponding change in the first output signal, and wherein the detected change indicates a transition between the articulation engaged state and the articulation disengaged state.
 14. The shaft assembly of claim 13, wherein the first sensor and the second sensor are optical sensors.
 15. The shaft assembly of claim 14, wherein the distal shaft portion comprises a first cylindrical portion including first slits, wherein the first slits are passed over the first sensor during the rotation of the distal shaft portion, and wherein the passing of the first slits over the first sensor changes the first output signal.
 16. The shaft assembly of claim 15, wherein the clutch assembly comprises a second cylindrical portion including second slits, wherein the second slits are passed over the second sensor during the rotation of the clutch assembly relative to the distal shaft portion, and wherein the passing of the second slits over the second sensor changes the second output signal.
 17. The shaft assembly of claim 16, wherein the first sensor and the second sensor are disposed on opposite sides of a support member.
 18. The shaft assembly of claim 17, wherein the support member extends between the first cylindrical portion and the second cylindrical portion.
 19. The shaft assembly of claim 18, wherein the first sensor is directed toward an inner surface of the first cylindrical portion.
 20. The shaft assembly of claim 19, wherein the second sensor is directed toward an outer surface of the second cylindrical portion.
 21. A shaft assembly for use with a surgical instrument, the shaft assembly defining a longitudinal axis extending longitudinally through the shaft assembly, wherein the shaft assembly comprises: a proximal shaft portion, comprising: a first sensor configured to generate a first output signal; and a second sensor configured to generate a second output signal; and a distal shaft portion comprising a switching component rotatable with the distal shaft portion about the longitudinal axis and relative to the proximal shaft portion, wherein the switching component is further rotatable relative to the distal shaft portion to transition the shaft assembly between an articulation engaged state and an articulation disengaged state; wherein rotation of the distal shaft portion relative to the proximal shaft portion is determined based on the first output signal, and wherein rotation of the switching component relative to the distal shaft portion is determined based on a combination of the first output signal and the second output signal. 